This invention relates to a method for removing lower molecular weight fractions of a poly(arylene sulfide) polymer and the composition produced thereby. More particularly, in a more preferred aspect, this invention pertains to removal of essentially all oligomers and non-polymeric impurities from a poly(phenylene sulfide) polymer and the composition produced thereby.
Poly(arylene sulfide) polymers are known in the art and have found wide use due to their desirable thermal and chemical resistance. Poly(arylene sulfide) polymers are useful in the formation of films, fibers, composites and molded parts by a variety of methods known to those of skill in the art.
Lower molecular weight fractions of poly(arylene sulfide) polymers, including oligomers and polymerization-by-products may contribute to certain processing and final product problems. Problems attributed to high oligomer concentrations in the polymer include mold plate out, die face build up, exhaust duct fouling, bubble formation in molded parts, corrosion, injection molding drool and off-gassing during injection molding, reduced mechanical properties and decreased weld line strength in parts having a weld line. Solvent extraction methods have been used to remove some of the oligomers from poly(phenylene sulfide) products, but a detrimental oligomer concentration usually remains after extraction. Thus, there still exists a need for an improved oligomer and non-polymeric impurity removal technique.